24
25 Troubleshooting (Sheet 3 of 4)
ComfortNet™
Thermostat Only
Symptoms of Abnormal Operation
(Legacy & ComfortNet™ Thermostat)
7-Segment LED
Codes
Characters
Will Alternate
Fault Description
Message Code
Possible Causes
Corrective Actions
Notes & Cautions
x Air handler blower fails to operate.
x Integrated control module LED display
provides indicated error code.
x ComfortNet™ thermostat “Call for
Service” icon illuminated.
x ComfortNet™ thermostat scrolls
“Check Air Handler” message.
b0
x Circulator blower
motor is not running
when it should be
running.
MOTOR
NOT RUN
b0
x Loose wiring connection at
circulator motor power leads
or circulator motor power
leads disconnected.
x Failed circulator blower motor.
x Tighten or correct wiring
connection.
x Check circulator blower
motor. Replace if necessary.
x Turn power OFF prior to
repair
x Replace circulator motor
with correct
replacement part.
x Air handler blower fails to operate.
x Integrated control module LED display
provides indicated error code.
x ComfortNet™ thermostat “Call for
Service” icon illuminated.
x ComfortNet™ thermostat scrolls
“Check Air Handler” message.
b1
x Integrated control
module has lost
communications with
circulator blower
motor.
MOTOR
COMM
b1
x Loose wiring connection at
circulator motor control leads.
x Failed circulator blower motor.
x Failed integrated control
module.
x Tighten or correct wiring
connection.
x Check circulator blower
motor. Replace if necessary.
x Check integrated control
module. Replace if
necessary.
x Turn power OFF prior to
repair
x Replace circulator motor
with correct
replacement part.
x Replace integrated
control module with
correct replacement
part.
x Air handler blower fails to operate.
x Integrated control module LED display
provides indicated error code.
x ComfortNet™ thermostat “Call for
Service” icon illuminated.
x ComfortNet™ thermostat scrolls
“Check Air Handler” message.
b2
x Circulator blower
motor horse power in
shared data set does
not match circulator
blower motor horse
power.
MOTOR
MISMATCH
b2
x Incorrect circulator blower
motor in air handler blower.
x Incorrect shared data set in
integrated control module.
x Verify circulator blower motor
horse power is the same
specified for the specific air
handler blower model.
Replace is necessary.
x Verify shared data set is
correct for the specific model.
Re-populate data using
correct memory card if
required.
x Turn power OFF prior to
repair
x Replace motor with
correct replacement
part.
x Use memory card for
the specific model
x Insert memory card
BEFORE turning power
ON. Memory card may
be removed after data is
loaded.
x Error code will be
cleared once shared
data and motor horse
power match.
x Turn power off before
removing memory card
x Air handler blower operates at reduced
performance.
x Airflow delivered is less than expected.
x Integrated control module LED display
provides b3 error code.
b3
x Circulator blower
motor is operating in a
power, temperature, or
speed limiting
condition.
MOTOR
LIMITS
b3
x Blocked filters.
x Restrictive ductwork.
x Undersized ductwork.
x High ambient temperatures.
x Check filters for blockage.
Clean filters or remove
obstruction.
x Check ductwork for blockage.
Remove obstruction. Verify
all registers are fully open.
x Verify ductwork is
appropriately sized for
system. Resize/replace
ductwork if necessary.
x See "Installation Instructions"
for installation requirements.
x Turn power OFF prior to
repair.
x Air handler blower fails to operate.
x Integrated control module LED display
provides indicated error code.
x ComfortNet™ thermostat “Call for
Service” icon illuminated.
x ComfortNet™ thermostat scrolls
“Check Air Handler” message.
b4
x Circulator blower
motor senses a loss
rotor control.
x Circulator blower
motor senses high
current.
MOTOR
TRIPS
b4
x Abnormal motor loading,
sudden change in speed or
torque, sudden blockage of air
handler blower/coil air inlet or
outlet.
x High loading conditions,
blocked filters, very restrictive
ductwork, blockage of air
handler blower/coil air inlet or
outlet.
x Check filters, filter
grills/registers, duct system,
and air handler blower/coil air
inlet/outlet for blockages.
x Turn power OFF prior to
repair.
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